Efficient way to join elements under a conditional











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2
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I am solving a certain challenge given by my friend.



I want to print the first day of the year if it is not a leap year, while I want both first and second days if it is a leap year.



I want to know if there is an efficient way to rewrite this piece of code:



If[Mod[year,4]==0,DayName/@{{year,1,1},{year,1,2}},{DayName[{year,1,1}]}]









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  • 1




    As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
    – Lonidard
    Dec 3 at 22:27















up vote
2
down vote

favorite












I am solving a certain challenge given by my friend.



I want to print the first day of the year if it is not a leap year, while I want both first and second days if it is a leap year.



I want to know if there is an efficient way to rewrite this piece of code:



If[Mod[year,4]==0,DayName/@{{year,1,1},{year,1,2}},{DayName[{year,1,1}]}]









share|improve this question


















  • 1




    As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
    – Lonidard
    Dec 3 at 22:27













up vote
2
down vote

favorite









up vote
2
down vote

favorite











I am solving a certain challenge given by my friend.



I want to print the first day of the year if it is not a leap year, while I want both first and second days if it is a leap year.



I want to know if there is an efficient way to rewrite this piece of code:



If[Mod[year,4]==0,DayName/@{{year,1,1},{year,1,2}},{DayName[{year,1,1}]}]









share|improve this question













I am solving a certain challenge given by my friend.



I want to print the first day of the year if it is not a leap year, while I want both first and second days if it is a leap year.



I want to know if there is an efficient way to rewrite this piece of code:



If[Mod[year,4]==0,DayName/@{{year,1,1},{year,1,2}},{DayName[{year,1,1}]}]






list-manipulation






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asked Dec 3 at 20:02









Exp ikx

1436




1436








  • 1




    As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
    – Lonidard
    Dec 3 at 22:27














  • 1




    As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
    – Lonidard
    Dec 3 at 22:27








1




1




As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
– Lonidard
Dec 3 at 22:27




As an aside: leap years are not years which are multiples of 4, the definition is slightly more complex
– Lonidard
Dec 3 at 22:27










2 Answers
2






active

oldest

votes

















up vote
4
down vote



accepted










Here is an alternate solution not using If:



Table[ DayName[ {year, 1, x} ], {x, 1 + Boole[ LeapYearQ[{year} ]]} ]





share|improve this answer




























    up vote
    2
    down vote













    LeapYearQ should be more reliable, in particular since special rules apply if the year is divisible by 100 or 400.



    f = year [Function] If[
    LeapYearQ[{year, 1, 1}],
    DayName /@ {{year, 1, 1}, {year, 1, 2}},
    {DayName[{year, 1, 1}]}
    ]





    share|improve this answer





















    • Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
      – Exp ikx
      Dec 3 at 20:12










    • Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
      – Henrik Schumacher
      Dec 3 at 20:14










    • I'm concerned about efficiency since it's a challenge. Nothing much.
      – Exp ikx
      Dec 3 at 20:16











    Your Answer





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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    4
    down vote



    accepted










    Here is an alternate solution not using If:



    Table[ DayName[ {year, 1, x} ], {x, 1 + Boole[ LeapYearQ[{year} ]]} ]





    share|improve this answer

























      up vote
      4
      down vote



      accepted










      Here is an alternate solution not using If:



      Table[ DayName[ {year, 1, x} ], {x, 1 + Boole[ LeapYearQ[{year} ]]} ]





      share|improve this answer























        up vote
        4
        down vote



        accepted







        up vote
        4
        down vote



        accepted






        Here is an alternate solution not using If:



        Table[ DayName[ {year, 1, x} ], {x, 1 + Boole[ LeapYearQ[{year} ]]} ]





        share|improve this answer












        Here is an alternate solution not using If:



        Table[ DayName[ {year, 1, x} ], {x, 1 + Boole[ LeapYearQ[{year} ]]} ]






        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Dec 3 at 21:01









        sakra

        2,4781328




        2,4781328






















            up vote
            2
            down vote













            LeapYearQ should be more reliable, in particular since special rules apply if the year is divisible by 100 or 400.



            f = year [Function] If[
            LeapYearQ[{year, 1, 1}],
            DayName /@ {{year, 1, 1}, {year, 1, 2}},
            {DayName[{year, 1, 1}]}
            ]





            share|improve this answer





















            • Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
              – Exp ikx
              Dec 3 at 20:12










            • Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
              – Henrik Schumacher
              Dec 3 at 20:14










            • I'm concerned about efficiency since it's a challenge. Nothing much.
              – Exp ikx
              Dec 3 at 20:16















            up vote
            2
            down vote













            LeapYearQ should be more reliable, in particular since special rules apply if the year is divisible by 100 or 400.



            f = year [Function] If[
            LeapYearQ[{year, 1, 1}],
            DayName /@ {{year, 1, 1}, {year, 1, 2}},
            {DayName[{year, 1, 1}]}
            ]





            share|improve this answer





















            • Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
              – Exp ikx
              Dec 3 at 20:12










            • Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
              – Henrik Schumacher
              Dec 3 at 20:14










            • I'm concerned about efficiency since it's a challenge. Nothing much.
              – Exp ikx
              Dec 3 at 20:16













            up vote
            2
            down vote










            up vote
            2
            down vote









            LeapYearQ should be more reliable, in particular since special rules apply if the year is divisible by 100 or 400.



            f = year [Function] If[
            LeapYearQ[{year, 1, 1}],
            DayName /@ {{year, 1, 1}, {year, 1, 2}},
            {DayName[{year, 1, 1}]}
            ]





            share|improve this answer












            LeapYearQ should be more reliable, in particular since special rules apply if the year is divisible by 100 or 400.



            f = year [Function] If[
            LeapYearQ[{year, 1, 1}],
            DayName /@ {{year, 1, 1}, {year, 1, 2}},
            {DayName[{year, 1, 1}]}
            ]






            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Dec 3 at 20:07









            Henrik Schumacher

            47.4k466134




            47.4k466134












            • Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
              – Exp ikx
              Dec 3 at 20:12










            • Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
              – Henrik Schumacher
              Dec 3 at 20:14










            • I'm concerned about efficiency since it's a challenge. Nothing much.
              – Exp ikx
              Dec 3 at 20:16


















            • Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
              – Exp ikx
              Dec 3 at 20:12










            • Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
              – Henrik Schumacher
              Dec 3 at 20:14










            • I'm concerned about efficiency since it's a challenge. Nothing much.
              – Exp ikx
              Dec 3 at 20:16
















            Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
            – Exp ikx
            Dec 3 at 20:12




            Thanks for that tip. But is there still a better way to write the rest of the code? I mean specifically for DayName part.
            – Exp ikx
            Dec 3 at 20:12












            Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
            – Henrik Schumacher
            Dec 3 at 20:14




            Hm. What does "better" mean? Are you concerned about efficiency? Why? How many years do you want to test this way?
            – Henrik Schumacher
            Dec 3 at 20:14












            I'm concerned about efficiency since it's a challenge. Nothing much.
            – Exp ikx
            Dec 3 at 20:16




            I'm concerned about efficiency since it's a challenge. Nothing much.
            – Exp ikx
            Dec 3 at 20:16


















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